1. Field of the Invention
The present invention relates to power supply testing equipment for non-utility power generators, etc. set up in high-rise buildings or other facilities in order to cope with emergency situation such as power breakdown, thereby determining whether or not they are in good condition. In particular, this invention is concerned with a loading device assembly for so-called dry type testing equipment in which a plurality of resistors each formed of a metal member are used for testing purposes without recourse to resistance water.
2. Prior Art
Referring now to FIG. 4, there is shown a typical power supply testing system used for non-utility power generators. As illustrated, a rectangular tank 71, through which a current passes, is charged with resistance water 72 of about 20.degree. C. While three pairs of vertically movable electrode plates 73 and 73 extending in three directions are immersed in the water 72, power is supplied from a non-utility power generator (not shown) between the electrode plates 73 and 73 for the time required to test and confirm its performance such as its power generating capability or its serviceability.
Referring to the typical testing procedure of this type of testing equipment, there is constantly a current of about 642.6 A, when power is supplied from a non-utility power generator working at an output of 1000 KVA, a power factor of 0.8 and a voltage of 415 volts between the electrode plates 73 and 73 in the tank 71.
This power generator is determined to have given power generating capability and serviceability, if there is no fault in its performance when power supply is continued for, e.g., 3 hours.
However, the resistance water 72 in the tank 71 increases in temperature due to the power supply and reaches as high as about 80.degree. C. when it overflows a drainage port 75, as illustrated.
To what degree currents are passed between the electrode plates 73 and 73 through the resistance water 72 is determined largely by the temperature rise or fall of the resistance water 72 and the degree of contamination of the resistance water 72. This in turn leads to a variation in the preset testing conditions, say, an output of 1000 KVA, a power factor of 0.8, a voltage of 415 V and a current of 642.6 A, under which the non-utility power generator works to supply power between the electrode plates 73 and 73 in the tank 71, thus resulting in a current exceeding 642.6 A flowing through the tank 71.
For that reason, there is often an overload on the generator and the associated engine.
Thus, the conventional testing equipment is designed to keep a current passing through it from exceeding a preset value of 642.6 A. For instance, this is achieved by moving the electrode plates 73 vertically to regulate the current-passing areas thereof in the resistance water 72 or supply an additional amount of fresh, low-temperature resistance water 72 through a water supply port 74, thereby limiting the temperature rise of the resistance water 72 in the tank 71.
However, the above conventional testing equipment is of size so large that it is very inconvenient to carry to where the power generator testing is needed and much time and labor are needed until it is set up.
No precise control of the electrode plates 73 is achieved as well, because much difficulty is involved in their vertical movement.
Another grave problem with this equipment is that it needs a continuous supply of fresh resistance water 72, which must immediately be discarded. Not only is the use of such a large quantity of water economically unfavorable, but the resistance water 72, once used, must be inconveniently discharged as well, thus creating environmental problems.
In order to provide a solution to the above problems, we have already come up with a small, economical and safe testing system which can test a non-utility power generator regardless of where it is set up, prevent an unusual current increase during testing by simple operation and make good use of resistance water, as set forth in JP-A-62-204866, JP-A-1-202554, JP-A-2-82183, JP-A-2-89754, JP-A-2-249798, JP-A-2-86755, JP-A-3-76270 and JP-A-3-100180.
As illustrated schematically in FIG. 3, this testing system is built of a tank 81 charged therein with a resistance liquid 86, a plurality of electrodes 82, each being fixed at one end on the upper portion of the tank 81, extending downwardly through the tank 81 and immersed in the resistance liquid 86 for receiving power from the non-utility power generator to be tested, a plurality of movable insulators 83, each being disposed in the tank 81 for making the quantity of a current through the electrode 82 variable, and a fan for feeding air forcedly onto the surface of a radiator 84 which serves to cool the resistance liquid 86 in the tank 81 (and onto which water is jetted from a spray pipe).
This testing system enables load tests for non-utility power generators, etc. to be done with a simplified structure and with no need of using large amounts of water.
Dissatisfied with this testing system, we have embarked on developing visionary testing equipment which can dispense with resistance water entirely, and so have now accomplished this invention.
In some cases, non-utility power generators must be set up in intermountain remote districts--that are depopulated areas, where much difficulty is encountered in providing sufficiently large amounts of water.
In some cases, they must be tested even in snowy districts having a large snowfall, where considerable difficulty is again encountered in supplying a large quantity of water.
In particular, much difficulty is involved in making a dry type testing equipment for testing high-voltage large-capacity generators of the order of 6.6 KV in voltage and 2000 KW in capacity. This is not only because loading devices--serving as resistance elements--made up of a metal member are inevitably of large size and cost much, but also because it is difficult to provide a fine-adjusting mechanism for setting the load.
In the present disclosure, the "low-voltage type" and "high-voltage type" refer to generators of about 500 V or less and about 1000 V or more, respectively, and the small-capacitor type" and "large-capacity type" refer to generators of about 500 KW or less and about 800 KW or more, respectively.
A major object of this invention is to eliminate the above problems associated with conventional testing facilities by providing a loading device assembly which can be used in the absence of water, is inexpensive to assemble and allows simple and accurate testing of a high-voltage large-capacity power generator.